Tune-up extension for use with spark plugs for testing purposes



INVENTOR f; ATTOR may 3 J. L. M coRD' Filed Jan. 25, 1956 JZJJE L.Mafia/PD Sept. 23, 1958 TUNE-UP EXTENSION FOR USE'WITH SPARK PLUGS FORTESTING PURPOSES Un t St t P e t TUNE-UP EXTENSION FOR USE WITH SPARKPLUGS FOR TESTING PURPOSES Jesse Lee McCord, Covington, Ga.

Application January 25, 1956, Serial No. 561,238

Claims, (Cl. 339-252) This invention relates to ignition systems and hasmore particular reference to a tune-up extension for use with sparkplugs for testing purposes.

In tuning up internal combustion engines having high tension ignitionsystems and in testing the spark plugs of such systems to see whetherthey are skipping or are grounded out, and in carrying out various othertests, it is essential that the mechanic have access to the centralelectrode terminals of the spark plugs or the terminal connections ofthe spark plug ignition cables.

Todays modern cars usually have V-type engines and the spark plugs arein an extremely difficult place to reach; in addition, the centralelectrode terminal of each spark plug is usually covered by a resilientdielectric sleevelike protective member which fits over the ceramicinsulator of the plug and extends for several inches over theignitioncable attached thereto. 'In some instances, the sleeve is formedintegral with the cable and in others it is made separate. In tuning upmotors of this type, some mechanics, in order to find a conductorsurface for testing purposes, pierce the sleeve with a sharp instrumentto get contact with the spark plug electrode, or cut into the cable. Ineither case, such procedure will permit leakage of moisture into thecable or sleeve and possibly cause faulty performance. I

One object of the present invention is to provide a novel tune-upextension especially designed for use in making tests in ignitionsystems of the class wherein the terminal end of the spark plug cable iscovered by a resilient cover member adapted to snugly fit over the upperportion of the insulator of the spark plug when the cable is attachedthereto, comprising an elongated metallic member having one end adaptedto extend into the sleeve-like protective covering of the terminal endof a spark plug ignition cable and be detachably connected to the cableconductor, and the other end adapted to be detachably at- I 'tached tothe spark plug central electrode terminal, whereby the tune-up extensionmay be quickly and readily connected to a spark plug and the ignitioncable therefor to provide an exposed conductor surface easily accessiblefor testing purposes.

Another object of the present invention is to provide a tune-upextension device, as characterized above, which is adapted for use withignition systems of the type described above in which the spark plugcables approach the spark plugs in a transverse direction as well assystems in which the spark plug cables approach the spark plugs in anaxial direction.

A further object of the present invention is to provide a tune-upextension, as characterized above, which is relatively simple inconstruction and can be easily applied to the intended use.

Other objects and advantages of the invention will appear'in thefollowing specification when considered in connection withtheaccompanying drawing, wherein: Fig. 1 is a perspective View of a tune-upextension connector constructed in accordance with the present inventionand showing the manner in which it is "used 2,853,691 Patented Sept. 23,1958 to connect a conventional spark plug to an ignition cable of thetype in which the cable approaches the spark plug in a transversedirection;

Fig. 2 is a side elevational view, partly in cross section, showing themanner in which the tune-up extension is connected to the spark plugcable shown in Fig. 1;

Fig. 3 is a vertical sectional view showing the manner in which thetune-up extension is connected to the spark plug when employed with anignition cable of the type shown in Figs. 1 and 2; and

Fig. 4 is a side elevational view, partly in cross section, showing themanner in which the tune-up extension shown in Figs. 1, 2 and 3, isemployedto connect the spark plug to an ignition cable approaching thespark plug in an axial direction. 7

Referring now to the drawing, there is illustrated one embodiment of atune-up extension device constructed of about 1%" in length. The endportion 11, adapted to be readily attached to and removed from thecentral electrode terminal of a spark plug, has an axially extendingrecess or bore 13 formed therein with the outer end portion 14 of thebore having a diameter greater than the diameter of the inner endportion 15 thereof and of a size to slidably receive the terminal endportion of the central electrode of the spark plug so as to form anelectrical connection between'the members. A metallica ball 16 ismovable mounted within the inner end portion 15 of the bore 13 and isnormally resiliently held seated against a pair of opposed stop membersor projections 17, extending inwardly from the outer edge of the endwall of the portion 15, as by means of a coiled metal spring 18 whichbears against the ball and the bottom of the bore 13. The end portion 11is also provided with a transverse bore 19 which intersects the bore v13at right angles and is, so positioned that'the ball 16 projectsthereinto when held against the stop projections 17. The end portion 12of the cylindrical member 10, which is adapted to be connected to theterminal connector of a spark plug cable, is made of a size and shapegenerally conforming to the size and shape of the terminal end portionof the central electrode of the spark plug and is shown as having acircumferential groove 20 formed thereon adjacent its outer end for apurpose hereinafter to be described.

In Figs. 1, 2 and 3, there is illustrated the manner in which thetune-up extension is employed to connect the central electrode terminalof the spark plug to the ignition cable thereto in ignition systems ofthe type in which the ignition cable approaches the spark plug in atransverse direction with respect to the central electrode terminal ofthe plug and carries a snap-on terminal connector housed in anelbow-shaped tubular shield having one end portion adapted to snugly fitover the upper end portion of the porcelain insulator when the snap-onterminal connector is connected to the central electrode terminal of theplug. As there shown, the spark plug P, which may be of any usual type,includes a metal base 21 having a threaded lower end for securing in theusual cylinder head or block of an engine, not shown, a ceramicelectrode, the upper terminal end 23 of which extends above theinsulator and is provided with a circumferential groove 24 for receivingresilient detent means carried by the connectorof the ignition cable toprovide a snap-on connection between the two members.

Thespark plng ignition cable C has the terminal end of its.conductoniconnected to a snapon' type connector 25 which is enclosedinamelbowphapedtubulap shield fitting 26 made of. elasticcdielectric;material such as rubber or neoprene or the like.

The tubularshield fitting 26'includes an upper leg 27 which extendsoveriand embraces the. end portion of the insulating covering of thecable C and a lower leg 28 which is adapted to snugly fit over theinsulator 22 of the spark plug. i

The snap-on terminal connector 25 may be of any usual construction andis shown. in theform ,ofa right angle ,tubular member having its upperleg 29 extending into theupper leg portion of the shield fitting andconnected to the end'of the conductorof the ignition cable in anysuitable manner and havingits lower leg 30 extending into the lower leg28 of theishield fittingin position to enp and connected to the end ofthe conductor of the ignition til cable in any suitable manner andhaving its lower end portion 30 extending into the lower portion 28' ofthe shield fitting in position to engage the terminal end 23 of thecentral electrode of the spark plug when it is received in the lower endportion of the shield fitting. The lower portion 30' of thezconnector 25is slotted to make it more resilient and carries one or morehinwa dlyproa snap-on connection between the tw-ozrnembersn. The

gage the terminal end 23of the central electrode of the spark plug whenit is reecivedin the lower leg of the shieldfitting. The lower leg 30 ofthe connector 25 is slotted to make it more resilient and carries one ormore inwardly projectingdetents 31 adapted to engage in the groove 24 ofthe eletcrode terminal 23 to make a snapon connection between the twomembers.

In using the tuneup extension of the invention with ignition systems ofthe type illustrated in Figs. land 2, the end portion 12 of the tune-upextension is inserted into the lower leg 28 of the shield fitting 26 andinto the lower leg of the connector 25 until the detents 31 of theconnector 25 are resiliently pressed into the groove formed on the endportion 12 of the tune-up extension to make a snap-on connection betweenthe two members which is easily made and broken, yet provides a goodelectrical connection between the two members. The end portion 11 of thetune-up extension is mounted on the spark plug with the terminal end 23of the central electrode received in and extending through thetransverse bore 19 therein, and with the bail 16 being spring pressedinto the groove 24 formed in the electrodeterminal, thus forming asecure snap-on connection which may. easily be made or broken andprovides a good electrical connection between the two members.

In Fig. 4 there is illustrated the manner in which the tune-up extensionis employed to connect the central electrode terminal of a spark plug tothe ignition cable thereto in ignition systems of the.type in which theignition cables approach the spark plug in an axial direction withrespect to the central electrode terminal and carries a snap-on terminalconnector housed in a resilient sleevelikeco-vering adapted to snuglyfit over the upper end portion of the insulator of the spark plug whenthe snapon terminal connector is connected. to the electrode terrninalof the plug.

As there shown, the spark plug P is identical in construction to thespark plug P shown in Fig. 1, and includes the ceramic insulator 22carried by the base and enclosing the central electrode, the upperterminal end 23 of which extends above the insulator and is providedwith a circumferential groove 24.

The spark plug ignition cable C has the terminal end of its conductorconnected to a snap-on type connector 25' which is enclosed in a tubularshield fitting 26' made of elastic dielectric material such as rubber,neoprene, or the like. The tubular shield fitting 26' includes an upperportion 27 which extends over and embraces the end portion of the.insulating covering of the cable C and a lower portion 28' which isadapted to fit over the insulator 122 of the spark plug. The snap onconnector 25'may be of any usual construction and is shown'in theform ofa metal tubular rnember having its upper end portion 29 extending intotheupper portion 21' of the shield fitting end portion 11 of thetune-upextension isxmounted 0n the spark plug with the terminal; end 23 ofthewcentral electrode received in the enlarged portion 14 of theraxialbore 13 formed therein, with the extreme end of the terminal 23 engagingthe ball 16 mounted in thellPP r portion 15 of the axialfibore 13,thereby insuringa good electrical connection between the tune-upextensionand the central electrode terminal.

from the foregoing, the manner of using he tune-up extension in; testinga spark plug is believed apparent.

The mechanic merely hasto disconnect the ignition cable from the plugandconnect the tune-up extension to the plug and cable, as abovedescribed. Hewillthenhave an exposed conductor surface to do histesting' without going to a lot of trouble and possibly injuring thshield protector or ignition cable, or burn his hands eatching for aplace of contact.

The invention further contemplates the provision'pf a set of tune-upextensions for use with ignitionsystems of the type described herein, sothat each spark plug may be connected to its ignition cable by a tune-upextension, thus facilitating the setting of the'timer, detecting motornoises and performing various other tests.

7 Obviously, the invention is not restricted to the-particularembodiment thereof herein shown; and describcd;'but is capable of manychanges within the scope of the appended claims.

What is claimed is: 1.; For use in an ignition system of theclass-,-;yvh erei each spark plugignition cable has a snap-on connectorhoused in an elongated sleeve-like shield member made of resilientdielectric material and having one end portion adapted to fit over theupper portion of thespark plug insulator when the snap-onconnector ofthe; cable is connected to the central electrode of the spark plug, thecombination with said sleeve-like shield member of means for providingan easily accessible contact surface in the ignition circuit to thespark plug for testing purposes, comprising an elongated metal tune-upextension .member having one end portion conforming generally in andbeing detachably connected to the central electrode of the spark plug.

2. Apparatus as set forth in claim 1, wherein the end portion of saidtune-up member extension, projecting outwardly from said sleeve-likeshield member is provided with a transverse bore in which the terminalof the central .,-.electrode of. the spark plug is slidably received to,make

. a detachable connection therebetween.

3, .Apparatus as set forthin. claim 1,.wl1erein the, end portion of saidtune-up..extension rnember projecting outwardly from said sleeve-likeshieldmember is provided with an axial bore in which the terminal of thecentral electrode of the spark plug is slidably received to make adetachable connection therebetween.

4. Apparatus as set forth in claim 1, wherein the end portion of saidtune-up extension member projecting outwardly from said sleeve-likeshield member is provided with an axial bore and a transverse bore whichintersects at right angles, in either of which bores the terminal of thecentral electrode of the spark plug is slidably received to make adetachable connection between the spark plug central electrode and thetune-up extension member; and wherein resilient detent means are carriedby the tune-up extension member and positioned to be urged into contactwith the terminal of the central electrode when it is receivedin eitherof the two bores.

5. Apparatus as set forth in claim 4, wherein said resilient detentmeans includes a metal ball mounted in said axial bore; stop means forretaining the ball in 20 said axial bore and positioned to permit theball to project part way into said transverse bore when the ball engagesthe stop means; and a coiled metal spring mounted in said axial borenormally resiliently holding said ball pressed against said stop means,the construction and arrangement being such that said resilient detentmeans insures good electrical connection between said tune-up extensionmember and the terminal of the central electrode of the spark plug whensaid terminal is received in either of the two bores.

References Cited in the file of this patent UNITED STATES PATENTS1,376,844 Weber May 3, 1921 1,457,570 Guthard June 5, 1923 1,814,997Wittner July 14, 1931 1,926,163 Mohr Sept. 12, 1933 2,024,814 Bell Dec.17, 1935

